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Electrical Formulas and Calculators

ALLOWABLE AMPACITIES INSULATED CONDUCTORS (IN A RACEWAY) TABLE 310-16 2005 NEC

  Temperature Rating of Conductor
  60°C 75°C 90°C 60°C 75°C 90°C
AWG   THW     THW  
  Types TW,
UF		 THWN   Types TW,
UF		 THWN  
MCM USE THHN USE THHN
  COPPER ALUMINUM OR COPPER-CLAD ALUMINUM
18 ----- ----- 14* ----- ----- -----
16 ----- ----- 18* ----- ----- -----
14 20* 20* 25* ----- ----- -----
12 25* 25* 30* 20* 20* 25*
10 30* 35* 40* 25* 30* 35*
8 40 50 55 30 40 45
6 55 65 75 40 50 60
4 70 85 95 55 65 75
3 85 100 110 65 75 85
2 95 115 130 75 90 100
1 110 130 150 85 100 115
1/0 125 150 170 100 120 135
2/0 145 175 195 115 135 150
3/0 165 200 225 130 155 175
4/0 195 230 260 150 180 205
250 215 255 290 170 205 230
300 240 285 320 190 230 255
350 260 310 350 210 250 280
400 280 335 380 225 270 305
500 320 380 430 260 310 350
600 355 420 475 285 340 385
700 385 460 520 310 375 420
750 400 475 535 320 385 435

* Unless otherwise specifically permitted in 240.4(E) or 240.4 (G), the overcurrent protection shall not exceed 15 amperes for 14 AWG, 20 amperes for 12 AWG, and 30 amperes for 10 AWG copper; or 15 amperes for 12 AWG and 25 amperes for 10 AWG aluminum and copper-clad aluminum after any correction factors for ambient temperature and number of conductors have been applied.